Buggy code:
public class MainWindow extends ApplicationWindow { private Action actionQuitter ; private Action actionDemarrer ; private Action actionPauser ; private Action actionArreter ; private Action actionOuvrir ; private Action actionSetAuto ; private Action actionSetManuel ; private VueHall vueHall ; @ Getter private Simulation simulation ; private PropertiesWidget propertiesWidget ; private Button btnManuel ; private Button btnAutomatique ; public MainWindow ( ) { } @ Override protected Control createContents ( Composite parent ) { parent . setSize ( new Point ( 400 , 400 ) ) ; Composite container = new Composite ( parent , SWT . NONE ) ; container . setLayout ( new GridLayout ( 3 , false ) ) ; <START_BUG> vueHall = new VueHall ( container , SWT . NONE ) ; <END_BUG> vueHall . setLayoutData ( new GridData ( SWT . FILL , SWT . FILL , false , true , 2 , 3 ) ) ; vueHall . setBackground ( SWTResourceManager . getColor ( COLOR_WHITE ) ) ; simulation = new Simulation ( vueHall ) ; Composite composite = new Composite ( container , SWT . NONE ) ; composite . setLayoutData ( new GridData ( SWT . FILL , SWT . FILL , false , false , 1 , 2 ) ) ; composite . setLayout ( new org . eclipse . swt . layout . FillLayout ( SWT . HORIZONTAL ) ) ; btnManuel = new Button ( composite , SWT . TOGGLE ) ; btnManuel . addSelectionListener ( new SelectionAdapter ( ) { @ Override public void widgetSelected ( SelectionEvent e ) { actionSetManuel . run ( ) ; } } ) ; btnManuel . setText ( "Manuel" ) ; btnAutomatique = new Button ( composite , SWT . TOGGLE ) ; btnAutomatique . addSelectionListener ( new SelectionAdapter ( ) { @ Override public void widgetSelected ( SelectionEvent e ) { actionSetAuto . run ( ) ; } } ) ; btnAutomatique . setText ( "Automatique" ) ; Group grpProperties = new Group ( container , SWT . NONE ) ; GridData gd_grpProperties = new GridData ( SWT . FILL , SWT . FILL , false , false , 1 , 2 ) ; gd_grpProperties . minimumWidth = 150 ; gd_grpProperties . widthHint = 200 ; grpProperties . setLayoutData ( gd_grpProperties ) ; grpProperties . setLayout ( new org . eclipse . swt . layout . FillLayout ( SWT . HORIZONTAL ) ) ; grpProperties . setText ( "Propriétés" ) ; propertiesWidget = new PropertiesWidget ( grpProperties , SWT . NONE , null ) ; simulation . setPropertiesWidget ( propertiesWidget ) ; CLabel lblVitesse = new CLabel ( container , SWT . NONE ) ; lblVitesse . setLayoutData ( new GridData ( SWT . RIGHT , SWT . CENTER , true , false , 1 , 1 ) ) ; lblVitesse . setAlignment ( RIGHT ) ; lblVitesse . setText ( "Vitesse<seq2seq4repair_space>de<seq2seq4repair_space>la<seq2seq4repair_space>simulation" ) ; Scale sclVitesse = new Scale ( container , SWT . NONE ) ; GridData gd_sclVitesse = new GridData ( SWT . LEFT , SWT . CENTER , false , false , 1 , 1 ) ; gd_sclVitesse . widthHint = 100 ; gd_sclVitesse . minimumWidth = 100 ; sclVitesse . setLayoutData ( gd_sclVitesse ) ; return container ; } private void createActions ( ) { } @ Override protected MenuManager createMenuManager ( ) { } @ Override protected ToolBarManager createToolBarManager ( int style ) { } @ Override protected StatusLineManager createStatusLineManager ( ) { } public static void main ( String [ ] args ) { } @ Override protected void configureShell ( Shell shell ) { } }

Fix:
vueHall = new VueHall ( container , ( ( SWT . NONE ) | ( SWT . NO_BACKGROUND ) ) ) ;